Most commercial uplinks/downlinks are some form of synchronous data using some form of PSK modulation (BPSK , QPSK, 8PSK etc.) . The approximate data clock rate is known by the receiver. The receiver extracts clock information from the transmitted data stream to synchronize the receivers local clock using a form of phase lock loop. As long as the PLL can acquire and track the downlink clock information, the signal will stay locked and track the doppler change.

- Howie AB2S